82 CONTRIBUTIONS 
teeth. It has a distinct fosset, but unlike the genus 
generally in this, it is placed above the teeth, and directly 
at the point of the beak. We may, with great propriety, 
consider this to be the connecting link with the Pectunculi, 
the “nuance” being into that of the P. ellipsis (nobis). 
A more complete junction could scarcely be established. 
NM. Brogniarti.* Plate 3. Fig. 61. 
Description. Shell elliptically transverse, somewhat in- 
flated, rounded before, produced and truncate behind, 
nearly equilateral, furnished with sinuous transverse folds 
over the disk, and six granose ribs behind, which passing 
from the beaks to the posterior margin form two channels 
on each valve ; substance of the shell thick ; lunule lan- 
ceolate ; escutcheon inflected, lanceolate ; beaks small, 
pointed, concentrically folded; anterior series of teeth 
arched—posterior series inflected ; teeth pointed, angular, 
diminishing in size towards the beak ; fosset deep, trian- 
gular; cicatrices impressed ; excavation of the palleal 
impression small and rounded ; cavity of the shell rather 
shallow, furnished posteriorly with two channels on each 
valve; margin very minutely crenulate ; nacre not pearly. 
Diam. .3, Length .4, Breadth .8, of an inch. 
Observations. Among all the nucule I have not seen so 
beautiful a species as this; its fine form and adorned exte- 
rior are very remarkable. The folds are larger before the 
* Named after the distinguished geologist Al. Brogniart. 
